The invention generally relates to processes relating to forming microelectronic devices using carbon dioxide.
There are a number of lithography processes which are well known in the art used in conjunction with manufacturing microelectronic devices. A typical lithography process involves aligning and transferring a pattern from a template using optics onto a partially processed substrate (e.g., wafer) that has been coated with a photoresist. The resist is then developed and the resist image is thereafter transferred into the underlying material typically by a chemical and/or thermal step such as, for example, dry/wet etch, sinter, implant, etc. This process is often repeated many times (e.g., between 15 to 20) during the course of building a complex integrated circuit.
The above processing steps can result in distortions being present in the wafer. Thus, wafer handling during processing is extremely important. The wafer handling subsystem is believed to be largely responsible for the throughput of the processing tool. Accordingly, the wafer handling should be designed to minimize sources of possible contamination. A difficulty from a processing standpoint relates to the incompatibility of an organic or aqueous solvent based coating solution and the enclosed equipment (e.g., a vacuum environment) used for processing substrates that have developed photo resist images (positive or negative) formed therein.
U.S. Pat. No. 5,665,527 to Allen et al. proposes a process for generating a negative tone resist image comprising the steps of coating a substrate with a film of a polymeric composition comprising a polymer, a photosensitive acid generator, and acid labile groups, imagewise exposing the film to radiation to generate free acid, and developing the image with critical fluid, e.g., carbon dioxide.
Notwithstanding the above, there is a need in the art for processes for forming semiconductor devices that involve depositing, developing and stripping resists that may be carried out in an integrated closed system which uses a solvent which is relatively benign from an environmental perspective (e.g., carbon dioxide). Such a process would be highly advantageous in that it would reduce or obviate the repeated entry, removal, and re-entry steps that are inherent in non-integrated processes.
In one aspect, the invention provides a process of forming a resist image in a microelectronic substrate. The process comprises the steps of contacting the substrate with a first composition comprising carbon dioxide and a component selected from the group consisting of at least one polymeric material, at least one monomer, at least one polymeric precursor, and mixtures thereof to deposit the component on the substrate and form a coating thereon, then imagewise exposing the coating to radiation such that exposed and unexposed coating portions are formed, and then subjecting the coating to a second composition comprising carbon dioxide such that either one of the exposed or the unexposed coating portions are removed from the substrate and the other coating portion remains on the coating to form an image thereon (e.g., developing the image using carbon dioxide). For the purposes of the invention, the first and second compositions may be the same or different. In a preferred embodiment, each step may be performed in a closed system such that said process is an integrated process. For the purposes of the invention, the term xe2x80x9cclosed systemxe2x80x9d refers to a system that is not exposed to ambient conditions.
This and other aspects are described by the invention in greater detail herein.